If you look at the taxonomic classification there are 7 levels and they are 1. Kingdom; 2. Phylum; 3. Class; 4. Order; 5. Family; 6. Genus and 7. Species.
The taxonomic level phylum includes greatest number of species for a given genus.
The elements in each group have the same number of electrons in the outer orbital
This is possible because proteins are created from different combinations of amino-acids. While we only have 20 different kinds of aminoacids, these 20 kinds can create thousands of combinations that we can observe in our bodies and bodies of other mammals as well as other organisms.
